Methods for the treatment of cognitive disorders

ABSTRACT

The invention relates to the use of certain compounds which act as antagonists of 5-hydroxytryptamine (5-HT) at 5-HT 3  receptors for the treatment of cognitive disorders such as attentional and memory deficits and dementia states.

This application is a division of application Ser. No. 07/133,885, filed Dec. 16, 1987 now U.S. Pat. No. 4,985,437.

This invention relates to a new medical use for certain chemical compounds and pharmaceutical compositions containing them. In particular it relates to the use in the treatment of dementia and other cognitive disorders of certain compounds which act as antagonists of 5-hydroxytryptamine (5-HT) at receptors known in the art as 5-HT₃, 5-HT`M` or 5-HT `M`-like` receptors. Such receptors have been described for example by Fozard et al., Eur. J. Pharmacol., 1979, 59, 195-210; Ireland, Straughan and Tyers, Br. J. Pharmacol., 1982, 75, 16P; Humphrey, Neuropharm., 1984, 23, 1503-1510; Richardson et al., Nature, 1985, 316, 126-131; and Bradley et al., Neuropharm., 1986, 25, 563-576. Receptors of this type are now designated as 5-HT₃ receptors.

5-HT receptors of this type are located, for example, on the terminals of afferent sensory neurones, in the isolated quinea-pig ileum preparation and are also present in the central nervous system. Compounds which act as antagonists of 5-HT at 5-HT₃ receptors may be identified using standard tests, for example, in vitro by measuring their inhibition of the depolarising effect of 5-HT on the rat or rabbit isolated vaqus nerve, or the tachycardia produced by 5-HT in the rabbit isolated heart or the contraction produced by 5-HT in the guinea-pig isolated ileum, or in vivo by measuring their effect on the Von Bezold-Jarisch reflex (induced by 5-HT) as described, for example, in the above-mentioned references.

A variety of compounds which act as antagonists of 5-HT at 5-HT₃ receptors have been described in the art. Such compounds have been disclosed inter alia in published UK Patent Applications Nos. 2100259, 2125398, 2131420, 2132189, 2145416, 2152049, 2153821 and 2169292, published European Patent Applications Nos. 111608, 116255, 158265, 191562, 200444, 210840, 214772, 219193, 221702, 226267, 227215, 230718, 235878 and 242973, and published Australian Patent Application No. 87/67121. The compounds disclosed in published European Patent Application Nos. 13138, 67615, and 94742 have also been described as antagonists of 5-HT at 5-HT₃ receptors, in published European Patent Applications Nos. 215545 and 220011.

The compounds disclosed in these specifications have been described as being of use in a variety of conditions, including migraine.

We have now found that compounds which are disclosed in the above specifications and act as 5-HT antagonists at 5-HT₃ receptors are useful in the treatment of cognitive disorders such as attentional and memory deficits and dementia states. These types of condition occur in, for example, senile dementia of the Alzheimers type, ageing, cerebrovascular deficiency and Parkinson's disease.

Accordingly the invention provides a method of treatment of a subject, in particular a human subject, suffering from dementia or another cognitive disorder, which comprises administering to the subject an effective amount of a compound selected from compounds of formulae (I) to (VIII) as defined hereinafter or a physiologically acceptable salt or solvate thereof.

The effectiveness of the compounds for use according to the present invention in the treatment of cognitive disorders may be demonstrated in rats in the spontaneous alternation test and in marmosets given learning tasks in the Wisconsin General Test Apparatus.

References in this specification to treatment include prophylactic treatment as well as the acute alleviation of symptoms.

Particular compounds for use in the present invention are those which act as antagonists of 5-HT at 5-HT₃ receptors and are disclosed in published UK Patent Specifications Nos. 2100259, 2131420, 2132189, 2145416, 2152049, 2153821 and 2169292, published European Patent Specifications Nos. 13138, 67615, 111608, 116255, 158265, 191562, 200444, 210840, 219193, 221702, 226267, 227215, 230718, 235878 and 242973, published Australian Patent Application No. 87/67121, and compounds of formula (I) as defined hereinafter. Compounds of formula (I) are described in UK Patent Specification No. 2125398.

Preferred compounds for use according to the invention are those compounds which act as antagonists of 5-HT at 5-HT₃ receptors described in published UK Patent Specification Nos. 2100259, 2132189, 2152049 and 2153821, published European Patent Specification Nos. 13138, 116255, 200444, 221702, 226267, 235878 and 242973, published Australian Patent Application No. 87/67121, and compounds of formula (I) as defined hereinafter.

Particularly preferred compounds for use according to the present invention are those described in published UK Patent Specification No. 2100259, published European Patent Specification Nos. 200444 and 242973, and compounds of formula (I) as defined hereinafter.

A preferred group of compounds for use according to the invention, described in UK Specification No. 2125398, may be represented by the general formula (I): ##STR1## wherein R₁ and R₂ independently represent hydrogen, halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, hydroxy, amino, C₁₋₄ alkylamino, di(C₁₋₄)alkylamino, mercapto or C₁₋₄ alkylthio;

R₃ represents hydrogen, C₁₋₄ alkyl, C₃₋₅ alkenyl, aryl or aralkyl;

R₄ represents hydrogen, C₁₋₇ alkyl, C₃₋₅ alkenyl or aralkyl;

n is 2 or 3;

the free valence is attached to either fused ring, and the azabicyclic ring is in either the exo or endo configuration; and acid addition salts and quaternary ammonium salts thereof.

In the compounds of formula (I) R₁ and R₂ may, for example, independently represent hydrogen, halogen or C₁₋₄ alkyl, R₃ may be, for example, hydrogen or C₁₋₄ alkyl and R₄ may be, for example, hydrogen, C₁₋₇ alkyl or aralkyl. The carbonyl group is preferably attached to the 3-position of the indole ring. The azabicyclic ring is preferably in the endo configuration.

Another preferred group of compounds for use according to the invention, described in UK Specification No. 2100259, may be represented by the general formula (II): ##STR2## wherein R₅ represents C₁₋₄ alkyl, C₁₋₄ alkoxy, or halogen; and

R₆ and R₇ independently represent hydrogen, C₁₋₄ alkyl, C₁₋₄ alkoxy or halogen provided that R₆ is hydrogen when R₇ is hydrogen;

and pharmaceutically acceptable salts thereof.

A preferred class of compounds of formula (II) are those in which R₅ and R₇ are the same and each represents methyl, methoxy or chlorine, and R₆ represents hydrogen.

Yet another preferred group of compounds for use according to the invention, described in European Specification No. 200444, may be represented by the general formula (III): ##STR3## wherein Y is NH or O; and

p is 2 or 3;

and pharmaceutically acceptable salts thereof.

A further preferred group of compounds for use according to the invention, described in UK Patent Specification No. 2153821 and European Specifications Nos. 191562, 210840 and 219193, may be represented by the general formula (IV): ##STR4## wherein R⁸ represents a hydrogen atom or a group selected from C₁₋₁₀ alkyl, C₃₋₆ alkenyl, C₃₋₁₀ alkynyl, C₃₋₇ cycloalkyl, C₃₋₇ cycloalkylC₁₋₄ alkyl, phenyl or phenylC₁₋₃ alkyl, and in the case where Q represents a hydrogen atom, R⁸ may also represent --CO₂ R¹², --COR¹², --CONR¹² R¹³ or --SO₂ R¹² (wherein R¹² and R¹³, which may be the same or different, each represents a hydrogen atom, a C₁₋₆ alkyl or C₃₋₇ cycloalkyl group, or a phenyl or phenylC₁₋₄ alkyl group, in which the phenyl group is optionally substituted by one or more C₁₋₄ alkyl, C₁₋₄ alkoxy or hydroxy groups or halogen atoms, with the proviso that R¹² does not represent a hydrogen atom when R⁸ represents a group --CO₂ R¹² or --SO₂ R¹²);

one of the groups represented by R⁹, R¹⁰ and R¹¹ is a hydrogen atom or a C₁₋₆ alkyl, C₃₋₇ cycloalkyl, C₂₋₆ alkenyl, or phenylC₁₋₃ alkyl group, and each of the other two groups, which may be the same or different, represents a hydrogen atom or a C₁₋₆ alkyl group;

Q represents a hydrogen atom or a halogen atom or a hydroxy, C₁₋₄ alkoxy, phenylC₁₋₃ alkoxy or C₁₋₆ alkyl group or a group --NR¹⁴ R¹⁵ or --CONR¹⁴ R¹⁵ (wherein R¹⁴ and R¹⁵, which may be the same or different, each represents a hydrogen atom or a C₁₋₄ alkyl or C₃₋₄ alkenyl group, or together with the nitrogen atom to which they are attached form a saturated 5 to 7 membered ring);

and physiologically acceptable salts and solvates thereof.

A preferred class of compounds represented by the formula (IV) for use according to the present invention is that wherein R⁸ represents a hydrogen atom or a methyl, ethyl, propyl, prop-2-yl, prop-2-enyl or cyclopentyl group; R¹⁰ represents a hydrogen atom; and either R⁹ represents a methyl, ethyl, propyl or prop-2-yl group and R¹¹ represents a hydrogen atom or R⁹ represents a hydrogen atom and R¹¹ represents a methyl or ethyl group; and Q represents a hydrogen atom.

A still further preferred group of compounds for use according to the invention, described in European Patent Specification No. 242973, may be represented by the general formula (V): ##STR5## wherein Im represents an imidazolyl group of formula: ##STR6## R¹⁶ represents a hydrogen atom or a C₁₋₆ alkyl, C₃₋₆ alkenyl, C₃₋₁₀ alkynyl, C₃₋₇ cycloalkyl, C₃₋₇ cycloalkylC₁₋₄ alkyl, phenyl or phenylC₁₋₃ alkyl group;

R¹⁷ represents a hydrogen atom or a C₁₋₆ alkyl, C₃₋₆ alkenyl, C₃₋₇ cycloalkyl, phenyl or phenylC₁₋₃ alkyl group;

R¹⁸ and R¹⁹, which may be the same or different, each represents a hydrogen atom or a C₁₋₆ alkyl group;

one of the groups represented by R²⁰, R²¹ and R²², is a hydrogen atom or a C₁₋₆ alkyl, C₃₋₇ cycloalkyl, C₃₋₆ alkenyl, phenyl or phenylC₁₋₃ alkyl group, and each of the other two groups, which may be the same or different, represents a hydrogen atom or a C₁₋₆ alkyl group;

and physiologically acceptable salts and solvates thereof.

A preferred class of compounds represented by the formula (V) for use according to the present invention are those wherein R¹⁶ represents a hydrogen atom or a methyl, prop-2-enyl or cyclopentyl group; R¹⁷ represents a hydrogen atom or a methyl group; R¹⁸ and R¹⁹ each independently represent a hydrogen atom or a methyl group; R²⁰ and R²¹ each represent a hydrogen atom; and R²² represents a hydrogen atom or a C₁₋₃ alkyl group, most preferably methyl.

Another preferred group of compounds for use according to the invention, described in European Specification No. 235878 and Australian Specification No. 87/67121, may be represented by the general formulae (VI) and (VII) respectively: ##STR7## wherein L is NH or O;

R²³ and R²⁴ are independently selected from hydrogen, halogen, CF₃, C₁₋₆ alkyl, C₁₋₆ alkoxy, C₁₋₆ alkylthio, C₁₋₇ acyl, C₁₋₇ acylamino, C₁₋₆ alkylsulphonylamino, N-(C₁₋₆ alkylsulphonyl)-N-C₁₋₄ alkylamino, C₁₋₆ alkylsulphinyl, hydroxy, nitro or amino, aminocarbonyl, aminosulphonyl, aminosulphonylamino or N-(aminosulphonyl)-C₁₋₄ alkylamino optionally N-substituted by one or two groups selected from C₁₋₆ alkyl, C₃₋₈ cycloalkyl, C₃₋₈ cycloalkylC₁₋₄ alkyl, phenyl or phenylC₁₋₄ alkyl groups or optionally N-disubstituted by C₄₋₅ polymethylene;

Z is a moiety capable of hydrogen bonding to the NH group depicted in formula (VI);

D and E are independently selected from hydrogen or C₁₋₄ alkyl, or together are a bond;

R²⁵ and R²⁶ are independently selected from hydrogen, C₁₋₆ alkyl, C₂₋₆ alkenylC₁₋₄ alkyl, or together are C₂₋₄ polymethylene;

M is a group of formula (a), (b) or (c): ##STR8## wherein t is 2 or 3; u is 1 or 2; v is 1 to 3; w is 1 to 3; and R²⁷ or R²⁸ is C₁₋₇ alkyl, C₃₋₈ cycloalkyl, C₃₋₈ cycloalkylC₁₋₂ alkyl or C₂₋₇ alkenylC₁₋₄ alkenyl;

and pharmaceutically acceptable salts thereof.

Preferably L is NH; R²³ is often hydrogen and R²⁴ is hydrogen or a 4-substituent such as halogen or methoxy; Z is preferably C--OCH₃, C--OC₂ H₅, C--OC₃ H₇, C--CO₂ CH₃, C--CO₂ C₂ H₅ or SO₂ N(CH₃)₂ ; often D and E are both hydrogen; often R²⁵ and R²⁶ are both hydrogen; preferably t is 2 or 3 and u, v and w are 1 or 2; and R²⁷ /R²⁸ is preferably methyl or ethyl, most preferably methyl.

Yet another preferred group of compounds for use according to the invention, described in UK Specification No. 2152049, may be represented by the general formula (VIII): ##STR9## wherein R¹, R² and R³ are as defined for general formula (I) and G is a group of formula (d) or (e): ##STR10## wherein R²⁹ is C₁₋₄ alkyl and R³⁰ is methoxy; and pharmaceutically acceptable salts thereof.

Particularly preferred compounds for use according to the present invention are (3α-tropanyl)-1H-indole-3-carboxylic acid ester and endo-N-(9-methyl-9-azabicyclo[3,3,1]non-3-yl)-1-methylindazole-3-carboxamide and physiologically acceptable salts and solvates thereof.

Other preferred compounds for use according to the present invention are:

3-(5-methyl-1H-imidazol-4-yl)-1-(1-methyl-1H-indol-3-yl)-1-propanone;

1αH, 3α,5αH-tropan-3-yl-3,5-dimethylbenzoate;

and physiologically acceptable salts and solvates thereof.

Further preferred compounds for use according to the present invention are:

1αH,3α,5αH-tropan-3-yl-3,5-dichlorobenzoate;

indole-[5-(2-methyl-2-azabicyclo(2.2.2)octyl]-3-carboxylate;

1H-indol-3-yl-carboxylic acid (3R*,4S*)-1-azabicyclo-[2.2.1]hept-3-yl ester;

1H-indolyl-3-carboxylic acid 2S-(1-methyl-2-pyrrolidinylmethyl) ester;

4-amino-5-chloro-2-methoxy-N-(3-quinuclidinylmethyl)benzamide;

1-methyl-3-indazolecarboxylic acid (endo-8-methyl-8-azabicyclo [3,2,1] oct-3-yl)ester;

(±)4-amino-5-chloro-2-methoxy-N-(6'α-[4'-thia-1'-azabicyclo[3,3,1]nonyl])benzamide;

(±)4-amino-5-chloro-2-methoxy-N-(6'α-[4'-oxa-1'-azabicyclo[3,3,1]nonyl])benzamide;

and physiologically acceptable salts and solvates thereof.

The invention also provides a pharmaceutical composition which comprises an effective amount of at least one compound selected from compounds of formulae (I) to (VIII), for use in medicine, particularly human medicine, for the treatment of dementia and other cognitive disorders.

In a further aspect the invention provides for the use of a compound selected from compounds of formulae (I) to (VIII) for the manufacture of a medicament for the treatment of dementia and other cognitive disorders.

Pharmaceutical compositions for use according to the present invention may be formulated in conventional manner, optionally with one or more physiologically acceptable carriers and/or excipients. For example, the compounds described in the aforementioned patent specifications may be formulated in the manner described therein.

Compounds for use according to the present invention may be formulated for oral, buccal, parenteral, rectal or transdermal administration or in a form suitable for administration by inhalation or insufflation (either through the mouth or the nose).

For oral administration, the pharmaceutical compositions may take the form of, for example, tablets or capsules prepared by conventional means with pharmaceutically acceptable excipients such as binding agents (e.g. pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose); fillers (e.g. lactose, microcrystalline cellulose or calcium hydrogen phosphate); lubricants (e.g. magnesium stearate, talc or silica); disintegrants (e.g. potato starch or sodium starch glycollate); or wetting agents (e.g. sodium lauryl sulphate). The tablets may be coated by methods well known in the art. Liquid preparations for oral administration may take the form of, for example, solutions, syrups or suspensions, or they may be presented as a dry product for constitution with water or other suitable vehicle before use. Such liquid preparations may be prepared by conventional means with pharmaceutically acceptable additives such as suspending agents (e.g. sorbitol syrup, cellulose derivatives or hydrogenated edible fats); emulsifying agents (e.g. lecithin or acacia); non-aqueous vehicles (e.g. almond oil, oily esters, ethyl alcohol or fractionated vegetable oils); and preservatives (e.g. methyl or propyl-p-hydroxybenzoates or sorbic acid). The preparations may also contain buffer salts, flavouring, colouring and sweetening agents as appropriate.

Preparations for oral administration may be suitably formulated to give controlled release of the active compound.

For buccal administration the compositions may take the form of tablets or lozenges formulated in conventional manner.

Compounds for use according to the present invention may be formulated for parenteral administration by injection e.g. by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form e.g. in ampoules or in multi-dose containers, with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilising and/or dispersing agents. Alternatively, the active ingredient may be in powder form for constitution with a suitable vehicle, e.g. sterile pyrogen-free water, before use.

The compounds for use according to the present invention may also be formulated in rectal compositions such as suppositories or retention enemas, e.g. containing conventional suppository bases such as cocoa butter or other glycerides.

In addition to the formulations described previously, the compounds may also be formulated as a depot preparation. Such long acting formulations may be administered by implantation (for example subcutaneously, transcutaneously or intramuscularly) or by intramuscular injection. Thus, for example, the compounds for use according to the present invention may be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt.

The dose at which the compounds may be administered to man will depend upon the route of administration, the body weight of the patient, the severity of the condition to be treated and the potency of the compounds. For example, the compounds disclosed in the aforementioned patent specifications may be administered at doses in the ranges specified therein for the compounds, or at lower doses for example 0.5 μg to 20 mg e.g. 0.005-20 mg, preferably 0.05-10 mg per unit dose which may be administered, for example, 1 to 4 times per day.

Thus a unit dose of a compound of formula (I) as herein defined may contain from 0.2 to 250 mg of the active ingredient, and may be administered for example up to four times per day, such that the overall daily dose is in the range 0.5 to 500 mg.

A unit dose of a compound of formula (II) as herein defined may contain from about 0.5 to 100 mg of the active ingredient, usually 1 to 50 mg and preferably 3 to 30 mg, and may be administered, for example, from 1 to 4 times per day.

A unit dose of a compound of formula (III) as herein defined may contain 0.5 to 1000 mg of the active ingredient, for example 1 to 500 mg, and may be administered, for example, 1 to 4 times per day, such that the total daily dose is in the range 0.001 to 50 mg/kg, more usually 0.002 to 25 mg/kg.

A unit dose of a compound of formula (IV) as herein defined may contain 0.05 to 20 mg of the active ingredient, preferably 0.1 to 10 mg, and may be administered 1 to 4 times per day.

A unit dose of a compound of formula (V) as herein defined may contain 0.001 to 100 mg of the active ingredient, preferably 0.01 to 50 mg, and may be administered 1 to 4 times per day.

A unit dose of a compound of formula (VI) as herein defined may contain 0.05 to 1000 mg of the active ingredient, for example 0.1 to 500 mg, and may be administered, for example, 1 to 4 times per day, such that the total daily dose is in the range 0.0001 to 50 mg/kg, more usually 0.0002 to 25 mg/kg.

A unit dose of a compound of formula (VII) as herein defined may contain 0.05 to 1000 mg of the active ingredient, for example 0.5 to 500 mg, and may be administered, for example, 1 to 4 times per day, such that the total daily dose is in the range 0.0001 to 50 mg/kg, more usually 0.0002 to 25 mg/kg.

A unit dose of a compound of formula (VIII) as herein defined may contain from 0.1 to 250 mg of the active ingredient, and may be administered up to four times per day, such that the overall daily dose is in the range 0.5 to 500 mg.

The following examples illustrate pharmaceutical formulations for use according to the invention, containing either (3α-tropanyl)-1H-indole-3-carboxylic acid ester or 3-(5-methyl-1H-imidazol-4-yl)-1-(1-methyl-1H-indol-3-yl)-1-propanone as the active ingredient. Other compounds for use according to the invention may be formulated in a similar manner.

TABLETS FOR ORAL ADMINISTRATION

Tablets may be prepared by the normal methods such as direct compression or wet granulation.

The tablets may be film coated with suitable film forming materials, such as hyroxypropyl methylcellulose, using standard techniques. Alternatively the tablets may be sugar coated.

Direct Compression Tablet

    ______________________________________                                                             mg/tablet                                                  ______________________________________                                         Active Ingredient     0.50                                                     Calcium Hydrogen Phosphate BP*                                                                       87.25                                                    Croscarmellose Sodium NF                                                                             1.8                                                      Magnesium Stearate BP 0.45                                                     Compression weight    90.0                                                     ______________________________________                                          *of a grade suitable for direct compression.                             

The active ingredient is passed through a 60 mesh sieve, blended with the calcium hydrogen phosphate, croscarmellose sodium and magnesium stearate. The resultant mix is compressed into tablets using a Manesty F3 tablet machine fitted with 5.5 mm, flat bevelled edge punches.

Tablets of other strengths may be prepared by altering the ratio of active ingredient to excipients or the compression weight and using punches to suit.

CAPSULES

    ______________________________________                                                         mg/capsule                                                     ______________________________________                                         Active Ingredient 0.5                                                          *Starch 1500      98.5                                                         Magnesium Stearate BP                                                                            1.0                                                          Fill Weight       100.0                                                        ______________________________________                                          *a form of directly compressible starch.                                 

The active ingredient is sieved and blended with the excipients. The mix is filled into size No. 2 hard gelatin capsules using suitable machinery. Other doses may be prepared by altering the fill weight and if necessary changing the capsule size to suit.

SYRUP

This may be either a sucrose or sucrose free presentation.

    ______________________________________                                         Sucrose-Free             mg/5 ml dose                                          ______________________________________                                         Active Ingredient             0.5                                              Hydroxypropylmethylcellulose USP                                                                            22.5                                              (viscosity type 4000)                                                          Buffer                                                                         Flavour                                                                        Colour                       as required                                       Preservative                                                                   Sweetener                                                                      Purified Water BP     to     5.0 ml                                            ______________________________________                                    

The hydroxypropylmethylcellulose is dispersed in hot water, cooled and then mixed with an aqueous solution containing the active ingredient and the other components of the formulation. The resultant solution is adjusted to volume and mixed. The syrup is clarified by filtration.

INJECTION FOR INTRAVENOUS ADMINISTRATION

    ______________________________________                                                         mg/ml                                                          ______________________________________                                         Active ingredient 0.05        0.5                                              Sodium Chloride BP                                                                               as required as required                                      Water for Injection BP to                                                                        1.0 ml      1.0 ml                                           ______________________________________                                    

Sodium chloride may be added to adjust the tonicity of the solution and the pH may be adjusted, using acid or alkali, to that of optimum stability and/or facilitate solution of the active ingredient. Alternatively suitable buffer salts may be used.

The solution is prepared, clarified and filled into appropriate size ampoules sealed by fusion of the glass. The injection is sterilised by heating in an autoclave using one of the acceptable cycles. Alternatively the solution may be sterilised by filtration and filled into sterile ampoules under aseptic conditions. The solution may be packed under an inert atmosphere of nitrogen or other suitable gas.

SUPPOSITORY

    ______________________________________                                         Active Ingredient      0.5 mg                                                  *Witepsol H15 to       1.0 g                                                   ______________________________________                                          *Witepsol H15 is a proprietary grade of Adeps Solidus Ph. Eur.           

A suspension of the active ingredient is prepared in the molten Witepsol and filled, using suitable machinery, into 1 q size suppository moulds.

The efficacy of the compounds for use according to the invention in the treatment of cognitive disorders has been demonstrated in marmosets given learning tasks in the Wisconsin General Test Apparatus.

Test Compounds:

(3α-Tropanyl)-1H-indole-3-carboxylic acid ester and 3-(5-methyl-1H-imidazol-4-yl)-1-(1-methyl-1H-indol-3-yl)-1-propanone.

Marmoset Learning Tasks in the Wisconsin General Test Apparatus Introduction and Test Procedure

Common marmosets were tested for performance in a discriminative learning task and reverse learning task using the Wisconsin General Test apparatus described by Harlow H. F., Psychological Review, 56, 51-65, 1949. The experiments were essentially carried out following the experimental protocol of Baker H. F., Ridley R. M. and Drewett, B., Psychopharmacology, 91, 512-514, 1987. The test compound was administered into the hind leg of the marmoset as a subcutaneous (s.c.) injection in 1 ml of saline.

Results

Administration of either of the test compounds at a dose of 10 ng/kg s.c. twice a day throughout testing improved the performance of the marmosets in the reverse learning task. 

I claim:
 1. A method of improving cognition in a patient suffering from dementia or other cognitive disorder which comprises administering to the patient an effective amount for the treatment of said dementia or other cognitive disorder of a compound of formula III: ##STR11## wherein Y is NH or O; and p is 2 or 3; which compound acts as a 5-HT antagonist at 5-HT₃ receptors.
 2. A method of improving cognition in a patient suffering from dementia or other cognitive disorder which comprises administering to the patient an effective amount of endo-N-(9-methyl-9-azabicyclo[3,3,1]non-3-yl)-1-methyl-indazole-3-carboxamide or physiologically acceptable salt or solvate thereof, which compound acts as a 5-HT antagonist at 5-HT₃ receptors.
 3. A method according to claim 1 wherein said compound of formula III is adminsitered in a dose of 0.5 μg to 20 mg from 1 to 4 times per day.
 4. A method according to claim 2 wherein said compound of formula III is administered in a dose of 0.05 mg to 10 mg from 1 to 4 times per day. 